The present invention relates to a corrosion resistant primer and, more particularly, an epoxy corrosion resistant primer which is free of hexavalent chromium compounds.
Structural alloys, including alloys of aluminum, steel, etc., are commonly used in aerospace, marine, auto and other applications. Generally, these alloys are protected against corrosion by applying primers or organic coatings containing corrosion inhibitors. Typically, the corrosion resistant primers used for the structural alloys are solvent based epoxy primers which employ hexavalent chromium as an active corrosion inhibitor pigment additive. These primers rely on the hexavalent chromium for corrosion protection. All forms of hexavalent chromium are recognized by the United States National Institute of Environmental Health Sciences as a Group I known human carcinogen. In addition, again with the enactment of federal and state legislation to reduce hexavalent chromium volatile organic content (VOC) levels in paints and primers, considerable attention has been given to waterborne, solvent-borne, and/or water-reducible resin binders. Accordingly, the use of corrosion inhibiting compounds which contain forms of hexavalent chromium are subject to stringent regulation and control. It would be very beneficial to eliminate hexavalent chromium as a corrosion inhibiting additive to such primers.
Accordingly, it is the principle object of the present invention to provide a corrosion resistant primer which is free of hexavalent chromium.
It is a particular object of the present invention to provide an epoxy corrosion resistant primer as set forth above which is effective in preventing attack on structural metal alloys.
It is a still further object of the present invention to provide a corrosion inhibiting epoxy primer as set forth above which is effective against both general corrosion and pitting corrosion.
Further objects and advantages of the present invention will appear hereinbelow.